* {
  box-size: border-box; }

h1 {
  text-align: center; }

.actions {
  text-align: center;
  margin: 20px; }

.seno {
  float: left;
  padding: 20px;
  text-align: center; }

#canvas, #canvas2, #canvas3 {
  border: 1px solid #333;
  position: relative;
  float: left;
  width: 300px;
  height: 300px;
  margin: 0 auto; }

.cube {
  position: absolute;
  border: 1px solid #333; }
  .cube.active {
    background: #333; }
